I'd like to use a microspin column to purify 38-50bp oligonucleotide from excess nucleotides and enzyme. The Qiaquik columns from Qiagen seem ideal for this, but a critical buffer is lacking (a buffer designated "PN"). This buffer apparently contains sodium perchlorate. I'd like to use this buffer, but would prefer not to have to spend large bundles of money for a bulk solution when this is really a one-pot shot. Does anyone know the recipe for this buffer or of a similar buffer for my purposes?

Thanks in advance for the help,

Daniel Ciznadija

Hi Daniel,
I suggest you try the QiaexII kit, not the quiaquik or gel extraction kits. Those columns are only good for 70bp and larger DNA. The buffer PN is only available with the nucleotide removal kit (and columns with it) etc. We don't have that kit on hand, so I can't tell you off hand if there's anything else special about it. If you have the Qiagen gel extraction kit, look in there for the graph (it's on one of the first few pages) and that shows you the cut off. I think you're just below it. When I work with small DNA I gel purify using a TAE-Metaphor gel and then use the QiaexII kit. It's a really simple protocol and yields are higher than the spin column method, especially for your small piece of DNA. Sorry... I know that was probably not the answer you wanted. However, I know this method works, good luck.

Cheers,
Jess White

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